Na+ Channel Blockers

Question 1

Class IA (quinidine)

Answer 1

Moderate Na+ channel blockade, Inc. ERP (effective refractory period)

Question 2

Class IB (lidocaine)

Answer 2

Weak Na+ channel blockade, Dec. ERP

Question 3

Class IC (flecainide)

Answer 3

Strong Na+ channel blockade, Same ERP

Question 4

Na+ channel blockade ranking:

Answer 4

IC > IA > IB

Question 5

Increasing effective refractory period (ERP):

Answer 5

IA > IC > IB (decreases)

Question 6

Propranolol

Answer 6

• Some class I activity

- Adverse effects include bronchospasm, bradycardia, fatigue

Question 7

Acebutolol

Answer 7

Cardioselective beta-blocking drug, so better for use in patients with asthma (to avoid adverse effects like bronchospasm)

Question 8

Esmolol

Answer 8

Short acting blocker used primarily for intraoperative and acute arrhythmias

Question 9

Sotalol

Answer 9

Nonselective Beta-blocking drug that prolongs the action potential (delays the slow outward current of K+)